Today, rival network Orange denied that it had made an offer to buy out the company. Third-placed Orange, owned by France Telecom, has made several approaches for the UK's fourth-largest network over the past year but been rebuffed. More recently it has been trying to join T-Mobile's network-sharing deal with the market's newest entrant, 3, after its existing partner Vodafone signed up with O2 in March.

While there has been drawn out speculation about T-Mobile's future in the crowded UK market, it has reached fever pitch in recent days after it emerged that investment bank JP Morgan has approached Vodafone about the possibility of it making an offer. Vodafone is poring over the financial figures it has received before deciding whether to proceed with a bid. It has looked at the business before, having raised the possibility of swapping its Turkish business for T-Mobile UK in a move that would have given Deutsche Telekom a strong position in the eastern Mediterranean, as it controls Greek operator OTE. That idea, however, never got much beyond the drawing board.

Neither Orange nor O2 are understood to have received details of T-Mobile's UK business from JP Morgan, but O2 is understood to be very interested in examining the figures if it gets the chance.

Deutsche Telekom tried to play down talk of an imminent sale of T-Mobile, pointing out that the UK business has only just installed a new chief executive, Richard Moat, who started work last Friday. Deutsche Telekom chief executive René Obermann has previously said the company should be given a chance in the "medium term".

T-Mobile insiders reckon the UK business will need significant investment in order for it to claw its way back into the market and the appointment of JP Morgan to gauge interest in a potential exit is designed to provide an idea of its current valuation in the market. The board can then decide whether it is worth putting in the cash that will be needed to improve its position, or if it is better to cut and run. Analysts reckon T-Mobile UK is worth about £3bn, which is £1bn less than the cost of the licence to run next-generation 3G services that the company bought at the height of the dotcom boom.

It has also emerged that T-Mobile's crucial UK partner Virgin Media, which uses the company's network to offer its Virgin Mobile service, has a clause in its contract which would allow it to jump ship in the event of a change of ownership.

Virgin Mobile has more than 4 million customers on the T-Mobile network, boosting the company's subscriber numbers and helping to fill its network.

Switching Virgin Mobile to another network could actually help any potential buyer as it might reduce any regulatory scrutiny. But the knowledge that more than 4 million users of the T-Mobile network could vanish overnight could also reduce the amount a buyer would pay.